In general, mood is the feature of the verb that presents the
verbal action or state with reference to its actuality or potentiality.
Voice indicates how the subject relates to the action or state of the verb;
tense is used primarily to portray the kind of action. There
are four moods in Greek: indicative, subjunctive, optative, and imperative.
See further qualifications in Wallace.

A. The Indicative Mood

The indicative mood is, in general, the mood of assertion, or presentation
ofcertainty. It is not correct to say that it is the mood of
certainty or reality. This belongs to the presentation (i.e., the
indicative may present something as being certain or real, though
the speaker might not believe it).

1. Declarative Indicative

The indicative is routinely used to present an assertion as a non-contingent
(or unqualified) statement. This is by far the most common use.

Mark 4:3 The sower went out to sow.

John 1:1 In the beginning was the Word.

2. Interrogative Indicative

The indicative can be used in a question. The question expects an
assertion to be made; it expects a declarative indicative in the answer.
(This contrasts with the subjunctive, which asks a question of moral "oughtness"
or obligation, or asks whether something is possible.)

Matt 27:11 Are you the king of the Jews?

John 1:38 He said to them, "What do you seek?" And
they said to him, "Rabbi, .. where are you staying?"

3. Conditional Indicative

This is the use of the indicative in the protasis of the conditional
sentences. The conditional element is made explicit with the particle ei.
the first class condition indicates the assumption of truth for the
sake of argument, while the second class condition indicates the
assumption of an untruth for the sake of argument.

Matt 12:27 If I cast out demons by Beelzebul, by whom do your
sons cast them out?

John 5:46 If you believe Moses, you would believe me.

4. Potential Indicative

The indicative is used with verbs of obligation, wish, or desire, followed
by an infinitive. The nature of the verb root, rather than the indicative,
is what makes it look like a potential mood in its semantic force.

Luke 11:42 It was necessary [for you] to have done these things.

1Cor 11:7 A man should not cover his head.

5. Cohortative (Command, Volitive) Indicative

The future indicative is sometimes used for a command, almost always
in the OT quotations (because of a literal translation of the Hebrew).
However, it was used even in classical Greek, though infrequently.

Matt 19:18 You shall not murder, you shall not commit
adultery, you shall not steal, you shall not bear
false witness.

B. The Subjunctive Mood

The subjunctive is the most common of the oblique moods in the N.T.
In general, the subjunctive can be said to represent the verbal action
(or state) as uncertain but probable. It is not correct to call this
the mood of uncertainty because the optative also presents the verb as
uncertain. Rather, it is better to call it the mood of probability
so as to distinguish it from the optative. Still, this is an overly simplistic
definition in light of its usage in the NT.

[Wallace breaks the discussion down into the use of the subjunctive
in independent (categories 1-4) and dependent (categories 5-10) clauses.]

1. Hortatory (Volitive) Subjunctive [let us]

The subjunctive is commonly used to exhort or command oneself and one's
associates. This use of the subjunctive is used "to urge some one
to unite with the speaker in a course of action upon which he has alrady
decided" (Chamberlain, 83). Since there is no first person imperative,
the hortatory subjunctive is used to do roughly the same task. Thus this
use ofl the subjunctive is an exhortation in the first person plural.
The typical translation, rather than we should ..., is let us
...

Mark 4:35 And he said to them, ... "Let us go to the other
side."

2. Deliberative (Dubitative) Subjunctive

The deliberative subjunctive asks either a real or rhetorical
question. The semantics of the two are often quite different. Both imply
some doubt about the response, but the real question is usually
in the cognitive area (such as "How can we ...?" in which
the inquiry is about the means), while the rhetorical question is
volitive (e.g., "Should we ...?" in which the question
has to do with moral obligation). Both are fairly common with first person
verbs, though second and third person verbs can be found. The future indicative
is also used in deliberate questions, though the subjunctive is more common.

Matt 6:31 Do not be anxious, saying, "What should we eat?"
or "What should we drink?" or "What should we
wear?"

Mark 8:37 What can a person give in exchange for his life?

3. Emphatic Negation Subjunctive

Emphatic negation is indicated by ou me plus the aorist subjunctive
or, less frequently, ou me plus the future indicative. This is the strongest
was to negate something in Greek. One might think that the negative with
the subjunctive could not be as strong, as the neative with the indicative.
However, while ou + the indicative denies a certainty, ou me + the
subjunctive denies a potentiality. ou me rules out even the idea
as being a possibility.

Matt 24:35 My words willnot at all pass away.

John 10:28 I give them eternal life, and they will not at
all perish.

4. Prohibitive Subjunctive

This is the use of the subjunctive is a prohibition - that is, a negative
command. It is used to forbid the occurrence of an action. The structure
is usually me + aorist subjunctive, typicaly in the second person.
Its force is equivalent to an imperative after me; hence, it should be
translated Do not rather than You should not.

Matt 1:20 Donotbe afraid to take Mary as your
wife.

5. Subjunctive in Conditional Sentences

This is the use of the subjunctive in the protasis of conditional sentences.
The conditional element is made explicit by the particle ean. Both the
particle and the subjunctive give the condition a sense of contingency.

Matt 4:9 I will give you all these things, if you will fall down
and worship me.

Mark 5:28 She was saying [to hersef], "If only I touch his
garments, I will be healed."

6. Ina + the Subjunctive

The single most common category of the subjunctive in the NT is after
ina, comprising about one third of all subjunctive instances. There are
seven basic uses in this construction: Purpose, result, purpose-result,
substantival, complementary, and command.

a. Purpose

Matt 12:10 They questioned him, saying, "Is it lawful to heal on
the Sabbath?" in order that they might accuse him.

b. Result

John 9:2 Rabbi, who sinned, this man or his parents, with the result
that he should be born blind?

c. Substantival

Matt 18:6 [that a millstone should be tied around his neck] is
better for him

d. Epexegetical

Luke 7:6 I am not worthy [that you should enter under my roof].

e. Complementary

Matt 26:4 They counseled together [to arrest] Jesus in a sly
way and to kill (him)].

7. Subjuctive with Verbs of Fearing, Etc.

Me plus the subjunctive can be used after verbs of fearing, warning,
watching out for, etc. Not unusual in the better writers (Paul, Luke,
Hebrews), this construction serves as a warning or suggests caution or
anxiety.

Luke 21:8 Watch out that you arenotdecieved.

1Cor 8:9 Take care lest somehow this liberty of yours should become
a stumbling block to the weak.

8. Subjunctive in Indirect Questions

The subjunctive is sometimes used in indirect questions. In such a usage,
it follows the main verb, but appears awkward, even unconnected, in the
sentence structure. Because of this, the subjunctive (and its accompanying
interrogative particle) needs to be smoothed out in translation.

Matt 15:32 They have already been with me for three days and they do
not have anything to eat.

Luke 9:58 The Son of Man has no place where he could lay his
head.

9. Subjunctive in Indefinite Relative Clause

The subjunctive is frequently used after ostis (av/ean) or os (d) an.
The construction normally indicates a generic (or sometimes an uncertain)
subject; hence, the particle of contingency and the need for a subjunctive.
The construction is roughly the equivalent of a third class or fifth
class condition. The difference is that in indefinite relative clauses
the element of contingency is not that of time but of person. Hence, the
subjunctive is often translated like an indicative, since the potential
element belongs to the subject rather than the verb.

Mark 3:29 Whoeverblasphemes against the Holy Spirit never
has forgiveness.

John 4:14 Whoeverdrinks of the water that I will give
him will never thirst again

10. Subjunctive in Indefinite Temporal Clause

The subjunctive is frequently used after a temporal adverb (or improper
preposition) meaning until. It indicates a future contingency from
the perspective of the time of the main verb.

Matt 5:26 You will not all leave from there untilyou have
paid back the last cent.

John 13:38 The cock will not at all crow untilyou have denied
me three times.

C. The Optative Mood

There are less than 70 optatives in the entire NT. In general, it can
be said that the optative is the mood used when a speaker wishes to portray
an action as possible. It usually addresses cognition, but may be
used to appeal to the volition. Along with the subjunctive and imperative,
the optative is one of potential or oblique moods.

This is the use of the optative in an independent clause to express
an obtainable wish or a prayer. It is frequently an appeal
to the will, in particular when used in prayers.

Rom 3:3-4 If some did not believe, their unbelief will not nullify the
faithfulness of God, will it? (4) May it never be! But let
God be [found] true, and every man [be found] a liar

2. Potential Optative

This use of the optative occurs with the particle an in the apodosis
of an incomplete fourth class condition. It is used to indicate a consequence
in the future of an unlikely condition. There are no complete fourth class
conditions in the NT. The protasis (which also uses the optative) needs
to be supplied. The idea is If he could do something, he would
do this. Only a handful of examples occur in the NT, all in Luke's
writings.

Luke 1:62 They were making signs to his father as to what he would
want to call him

Acts 17:18 Some [of the philosophers] were saying, "What would
this babbler say?"

D. The Imperative Mood

The imperative mood is the mood of intention. It is the mood
furthest removed from certainty. Ontologically, as one of the potential
or oblique moods, the imperative moves into the realm of volition (involving
the imposition of one's will upon another) and possibility.

1. Command

The imperative is most commonly used for commands, outnumbering prohibitive
imperatives about five to one. The basic force of the imperative of command
involves somewhat different nuances with each tense. With the aorist, the
force generally is to command the action as a whole, without focussing
on duration, repetition, etc. In keeping with its aspectual force, the
aorist puts forth a summary command. With the present, the
force generally is to command the action as an ongoing process.
This is in keeping with the present's aspect, which portrays an internal
perspective.

Mark 2:14 Follow me!

Mark 6:37 Give them [something] to eat.

2. Prohibition

The imperative is commonly used to forbid an action. It is simply a
negative command me (or a cognate) is used before the imperative to turn
the command into a prohibition.

Matt 6:3 Do not let your left hand know what your
right hand is doing.

3. Request (Entreaty, Polite Command)

The imperative is often used to express a request. This is normally
seen when the speaker is addressing a superior. Imperatives (almost always
in the aorist tense) directed toward God in prayers fit this category.
The request can be a positive one or a negative one (please, do not
...); in such cases the particle me precedes the verb.

The imperative is rarely used to connote permission or, better, toleration.
This usage does not normally imply that some deed is optional or approved.
It often views that act as a fait accompli. In such instances, the
mood could almost be called "an imperative of resignation."'

Matt 8:31-32 "If you cast us out, send us into the herd of swine."
And he said to them, "Go!"

1Cor 7:15 If the unbeliever departs, let him depart

5. As a Stereotyped Greeting

Sometimes the imperative is used in a stereotyped manner in which it
has suppressed its original injunctive force. The imperative is reduced
to an exclamation. This occurs especially in greetings.